This invention is related to a dental X-ray diagnostic unit used to produce panoramic planigraphs of an object, with a radiation source, a cassette that exposes the X-ray film and moves during the exposure with respect to the radiation source, with an adjusting device that is used to move the radiation source and the cassette around the object, and with a slit stop located in the radiation path between the radiation source and the cassette to limit the radiation beam.
A dental X-ray diagnostic unit of this type is described in German patent application P 24 47 075.5. By means of this X-ray diagnostic unit, panoramic planigraphs of the jaw can be produced. For this purpose the patient's cranium is held steady in a head support. The X-ray tube and the cassette with the X-ray film are moved around the patient in such a way that an image of the entire jaw can be obtained on the film in a single exposure. The picture taken in this manner is a planigraph, in which a desired image quality required for a diagnosis is present only within a certain layer. The zones lying outside this clear layer appear as blurred images. With this process, the thickness of the clearly imaged layer is proportional to the respective radius of curvature of the layer and inversely proportional to the width of the radiation beam and accordingly also to the width of the slit stop that determines the width of the radiation beam.
In an X-ray diagnostic unit of this kind, it is desirable to increase the dosage from the radiation source during the exposure in the course of traversing specific areas, in particular the area of the spinal column.
The invention is designed to perform the function of producing a dental diagnostic unit of the type described above, in which the dosage can be optimally adjusted to the individual patient.